| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/static_assertions-1.1.0/src/assert_fields.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>assert_fields.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../normalize.css"><link rel="stylesheet" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../ayu.css" disabled><link rel="stylesheet" href="../../dark.css" disabled><link rel="stylesheet" href="../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../storage.js"></script><script defer src="../../source-script.js"></script><script defer src="../../source-files.js"></script><script defer src="../../main.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../static_assertions/index.html"><div class="logo-container"> |
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| </pre><pre class="rust"><code><span class="doccomment">/// Asserts that the type has the given fields. |
| /// |
| /// # Examples |
| /// |
| /// One common use case is when types have fields defined multiple times as a |
| /// result of `#[cfg]`. This can be an issue when exposing a public API. |
| /// |
| /// ``` |
| /// # #[macro_use] extern crate static_assertions; |
| /// pub struct Ty { |
| /// #[cfg(windows)] |
| /// pub val1: u8, |
| /// #[cfg(not(windows))] |
| /// pub val1: usize, |
| /// |
| /// #[cfg(unix)] |
| /// pub val2: u32, |
| /// #[cfg(not(unix))] |
| /// pub val2: usize, |
| /// } |
| /// |
| /// // Always have `val2` regardless of OS |
| /// assert_fields!(Ty: val2); |
| /// ``` |
| /// |
| /// This macro even works with `enum` variants: |
| /// |
| /// ``` |
| /// # #[macro_use] extern crate static_assertions; fn main() {} |
| /// enum Data { |
| /// Val { |
| /// id: i32, |
| /// name: String, |
| /// bytes: [u8; 128], |
| /// }, |
| /// Ptr(*const u8), |
| /// } |
| /// |
| /// assert_fields!(Data::Val: id, bytes); |
| /// ``` |
| /// |
| /// The following example fails to compile because [`Range`] does not have a field named `middle`: |
| /// |
| /// ```compile_fail |
| /// # #[macro_use] extern crate static_assertions; fn main() {} |
| /// use std::ops::Range; |
| /// |
| /// assert_fields!(Range<u32>: middle); |
| /// ``` |
| /// |
| /// [`Range`]: https://doc.rust-lang.org/std/ops/struct.Range.html |
| </span><span class="attribute">#[macro_export] |
| </span><span class="macro">macro_rules! </span>assert_fields { |
| (<span class="macro-nonterminal">$t</span>:ident::<span class="macro-nonterminal">$v</span>:ident: $(<span class="macro-nonterminal">$f</span>:ident),+) => { |
| <span class="attribute">#[allow(unknown_lints, unneeded_field_pattern)] |
| </span><span class="kw">const _</span>: <span class="kw">fn</span>() = || { |
| <span class="attribute">#[allow(dead_code, unreachable_patterns)] |
| </span><span class="kw">fn </span>assert(value: <span class="macro-nonterminal">$t</span>) { |
| <span class="kw">match </span>value { |
| $(<span class="macro-nonterminal">$t</span>::<span class="macro-nonterminal">$v </span>{ <span class="macro-nonterminal">$f</span>: <span class="kw">_</span>, .. } => {},)+ |
| <span class="kw">_ </span>=> {} |
| } |
| } |
| }; |
| }; |
| (<span class="macro-nonterminal">$t</span>:path: $(<span class="macro-nonterminal">$f</span>:ident),+) => { |
| <span class="attribute">#[allow(unknown_lints, unneeded_field_pattern)] |
| </span><span class="kw">const _</span>: <span class="kw">fn</span>() = || { |
| $(<span class="kw">let </span><span class="macro-nonterminal">$t </span>{ <span class="macro-nonterminal">$f</span>: <span class="kw">_</span>, .. };)+ |
| }; |
| }; |
| } |
| </code></pre></div> |
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